Various ring seals for use at the end of connector housing have been used. Kramer U.S. Pat. No. 3,206,226 discloses an annular seal ring having radially inner and radially outer sides defining smoothly convex surfaces extending across the width thereof and convex axial sides forming a pair of radially outer corners and a pair of radially inner corners. Greenwald U.S. Pat. No. 3,698,727 pertains to a seal ring which in cross-section is essentially U-shaped or J-shaped and having an elastomeric or garter spring core. Kramer U.S. Pat. No. 3,918,726 relates to another flexible seal member having an insert membrane embodied therein to provide reinforcement of the balance of the flexible seal against deformation and resistance to abrasion. The disclosure of Shire and Newman U.S. Pat. No. 3,695,639 is characterized by two generally ring shaped cells mounted in spaced side by side relationship at the end of a connector housing. The outer seal is generally circular in cross-section and includes a first leg, and a second smaller leg connected together by a web portion. The end of the connector tube is provided with formations for holding the seals in the housing. These formations may include first and second counterbores for positioning the inner seal in the end of the connector housing. The base of the second counterbore is normally in spaced relation to the inner side of the second leg to permit the legs of the inner seal to flex when a pipe mounted in the connector pivots or vibrates.
The basic purposes of these annular rings is to maintain a tight seal over the wide range of temperatures and conditions encountered in use. The environment encountered is typically that found in the heating and air conditioning ducts of a modern commercial jet transport airplane. The individual lengths of connector tube are flexible due to thermal expansion and contraction, placing substantial and repeated stress on the ring seals.
The prior patents discussed above treat the problem of seal wear due to abrasion caused by repeated flexing in several ways. The seals of the Kramer patents lack sufficient flexibility and have been generally rejected for all practical purposes.
The other two patents endeavored to provide flexibility. However, the seals disclosed therein are rather complex in manufacture involving composite structures or a plurality of individual components. In any case, the complexity creates opportunity for error in manufacture and installation, as well as necessarily involving high cost.
The present invention for the first time presents an integral annular seal which provides excellent sealing, high flexibility and resistance to abrasion. The seal of this invention is simpler to make and install in a connector and is believed to represent a significant advance over the seals of the prior art. It is to be expected that this new seal will be widely adopted by the commercial jet transport industry.